Cytotoxicity mediated by soluble macrophage product(s).

The soluble macrophage product(s) released by nonimmune mouse peritoneal macrophages exposed to endotoxin or from listeria-immune macrophages after incubation with specific antigen mediated cytotoxic activity against malignant cell types and, to a lesser extent, against normal cells. Only undiluted supernatants from nonimmune or listeria-immune macrophages cultured with medium 199 alone exerted some degree of cytotoxicity on the different target cell types tested. The macrophage product(s) retained cytotoxic activity storage at minus 20 degrees C, was stable when heated at 56 degrees C for 30 minutes, but was completely inactivated when exposed at 100 degrees C for 5 minutes. In the presence of 15 mug exogenous lysozyme/ml, the cytotoxic activity of the macrophage product(s) was significantly enhanced.